1. Field of the Invention
The present invention pertains to an intraocular lens, and more particularly, pertains to a dimpled YAG lens or YAG dimpled lens which includes a barrier rim, as well as YAG spacing geometrical section.
2. Background of the Invention
Prior art lenses with YAG spaces have not provided sufficient barriers which reduce the rate of capsular opacification from Elschnig's pearls. Two representative prior art intraocular lens patents are the Hoffer reissue patent No. 31,626 and the Myers reissue patent No. 31,998, which are designated in the art as YAG lenses
Evidence is also accumulating that insertion of a posterior chamber lens implant may reduce the rate at which the posterior capsule opacifies, particularly if the convex surface of the optic is posterior in broad opposition to the capsule. This is commonly referred to as the "barrier effect". No one to date has performed a careful prospective study to be certain that posterior chamber lenses are a barrier to Elschnig's pearl-type capsular opacification, but many experienced surgeons agree that there is a beneficial effect.
In my experience, approximately 1 percent of capsules opacify in the first year following extracapsular cataract extraction and posterior chamber lens implantation. The majority of these cases are from a fibrous metaplasia and not from Elschnig's pearls. After this first year, approximately 5 percent of capsules opacify each year up to my current follow-up of approximately five years leading to an incidence of approximately 20-25 percent after five years follow-up.
This is a lower incidence than was experienced utilizing extracapsular cataract extraction without posterior chamber lens implantation or with anterior chamber or iridocapsular lens implantation. This reduction in the rate of capsular opacification when utilizing a posterior chamber lens has also been documented by Pearce, Gills, Anis, Harris, McIntrye and others. One can often clinically observe this retardation in the progression of Elschnig's pearls as they approach a posterior chamber lens that has adhered to the posterior capsule. On the other hand., it is not yet known if this delay in posterior capsular opacification is permanent. With the passage of enough time an increasing percentage of capsules may be expected to opacify. Nonetheless, this reduced rate of opacification is a significant advantage.
The firm and broad contact of the lens implant optic to the posterior capsule mentioned earlier may also provide the advantage of reducing the incidence of capsular opacification from Elschnig's pearls. It has been the clinical impression of several surgeons that a relative barrier to cortical cell proliferation and late posterior capsular opacification can be obtained when the lens implant optic adheres to the posterior capsule. This barrier effect appears to delay the onset of capsular opacification. If a primary discission is performed, the lens optic will, in some cases, tamponade the vitreous in the posterior chamber and the capsule can re-adhere to the posterior convex surface of the lens implant thereby recreating a barrier between the anterior and posterior chamber. If a secondary discission is required, the optic-capsular adhesion can be readily separated with a discission needle.
The present invention overcomes the disadvantages of the prior art by providing a YAG dimpled or dimpled YAG intraocular lens with an effective barrier rim.